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"Evidence demonstrates that the authorized COVID-19 vaccines are both efficacious and effective against symptomatic, laboratory-confirmed COVID-19, including severe forms of the disease. In addition, a growing body of evidence suggests that mRNA COVID-19 vaccines also reduce asymptomatic infection and transmission. Substantial reductions in SARS-CoV-2 infections (both symptomatic and asymptomatic) will reduce overall levels of disease, and therefore, viral transmission in the United States. ... Data from multiple studies in different countries suggest that people vaccinated with Pfizer-BioNTech COVID-19 vaccine who develop COVID-19 have a lower viral load than unvaccinated people.(41-44) This observation may indicate reduced transmissibility, as viral load has been identified as a key driver of transmission.(45) Two studies from the United Kingdom found significantly reduced likelihood of transmission to household contacts from people infected with SARS-CoV-2 who were previously vaccinated for COVID-19.(25, 46)" https://www.cdc.gov/coronavirus/2019-ncov/science/science-br... "Two studies1,2 from Israel, posted as preprints on 16 July, find that two doses of the vaccine made by pharmaceutical company Pfizer, based in New York City, and biotechnology company BioNTech, based in Mainz, Germany, are 81% effective at preventing SARS-CoV-2 infections. And vaccinated people who do get infected are up to 78% less likely to spread the virus to household members than are unvaccinated people. Overall, this adds up to very high protection against transmission, say researchers." https://www.nature.com/articles/d41586-021-02054-z "COVID-19 vaccines appear to help prevent transmission between household contacts, with secondary attack rates dropping from 31% to 11% if the index patient was fully vaccinated, according to a Eurosurveillance study yesterday. The population-based data looked at the Netherlands from February to May, when the Alpha variant (B117) was dominant and the available vaccines were by Pfizer/BioNTech, AstraZeneca/Oxford, Moderna, and Johnson & Johnson." https://www.cidrap.umn.edu/news-perspective/2021/08/study-ti... "There has been good news, too, on the subject of viral load in breakthrough cases. Researchers in Israel studied vaccinated people who became infected. The viral load in these breakthrough cases was about three to four times lower than the viral load among infected people who were unvaccinated. Researchers in the U.K. reported a similar result. They also found that vaccinated people who became infected tested positive for about one week less than unvaccinated people." https://www.scientificamerican.com/article/the-crucial-vacci... |